Project Summary Funds are requested to provide partial support for the 8th International Symposium on the Biology of Vertebrate Sex Determination to be held in April of 2018. This meeting has been held at 3-year intervals since its inception in 1997. This unique meeting is attended by the entire international field working on diverse vertebrate systems, including amphibians, fishes, birds, reptiles, monotreme, marsupial, and eutherian mammals, including domesticated species, mice, and humans. It is nearly impossible to keep up with the advances made in so many diverse vertebrate systems. Therefore, the objective of this meeting is to exchange information, using a comparative approach to advance our understanding of the process of sex determination, sex differentiation and disorders of sexual development. Many collaborations resulted from the first seven symposia: reagents were exchanged, experiments planned and new ways of looking at sex determination discussed. ~70% of the participants of the 7th symposium were junior scientists, including graduate students, postdoctoral fellows, and assistant professors, providing a unique opportunity for interactions with senior leaders in the field. We expect the 8th symposium to be as productive and stimulating as the previous ones.